JPS59155530A - Combustion chamber structure of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent a spark plug from being fouled and misfiring from occurring due to the spark plug being directly hit by inflowing mixture by a structure wherein the spark plug is arranged at a position free from being directly hit by inflowing mixture and at the same time the velocity of mixture flow near the spark plug is fully raised by a guide wall formed along the peripheral edge of a combustion chamber. CONSTITUTION:A hemispherical combustion chamber 14 is concavedly arranged on a cylinder head 12. A suction passage 15 and an exhaust passage 16 are arranged in a crossflowing manner with respect to the combustion chamber 14 so as to connect to a suction port 17 and an exhaust port 18, both of which are respectively open to the combustion chamber 14. Further, the suction passage 15 points to a position deviated from the axis center of a cylinder. In this case, each spark plug 21 is positioned within a domain A, which is surrounded with a line l1 to connect the centers O1 of the respective suction ports 17 in the direction of line of cylinders, a line l2 to be normal to the line of cylinders and simultaneously tangent to an outer edge of the exhaust port 18, and the outer edges of the suction port 17 and of the exhaust port 18. Furthermore, a guide wall 22, which extends itself curvedly toward the inner peripheral side of a cylinder, is provided along the peripheral edge of the combustion chamber at a portion on the spark plug 21 side.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the structure of a combustion chamber of an internal combustion engine in which an intake passage and an exhaust passage are arranged in a cross-flow manner in a hemispherical combustion chamber.

As a combustion chamber structure suitable for operation with a relatively lean air-fuel mixture, an intake passage and an exhaust passage are arranged in a cross 70-shape in a hemispherical combustion chamber, and the intake passage is placed on one side from the cylinder axis. There are some systems that strengthen the intake swirl by directing it to a biased position, and use this swirl to achieve good combustion.
7-61884) or Figure 2 (% Publication No. 1973-
As shown in Japanese Patent Publication No. 10059), in the hemispherical combustion chamber l, the ignition plug 3 is arranged in front of the intake passage 2, that is, at a position where the intake passage 2 is directly directed, and a sufficient flow velocity in the vicinity of the ignition plug 3 is ensured. That's what I do.

However, in this way, the ignition plug 3 is located in front of the intake passage 2.
If the fuel mixture enters the combustion chamber 1, it will directly hit the ignition plug 3, and the ignition plug 3 will become supercooled and smoke, or the liquid fuel may adhere to it, causing a misfire. This results in deterioration of drivability and fuel consumption.

Particularly when the engine is operating at high speed with a large amount of intake air, it becomes difficult to operate near the stoichiometric air-fuel ratio, resulting in a significant increase in fuel consumption.

In the example shown in FIG. 2, a part of the intake passage 2 is covered with a guide wall 4, and the air-fuel mixture is directed toward the spark plug 3 by the guide wall 4. In this case, the guide wall 4 This has the disadvantage that the resistance during intake air flow increases, which limits the maximum output of the engine.

This invention was made in view of the above-mentioned conventional problems, and while the ignition plug is placed in a position where it is not directly hit by the inflowing air-fuel mixture, the flow velocity in the vicinity is sufficiently increased by a guide wall around the periphery of the combustion chamber. In this way, the purpose is to reliably prevent misfires and smoldering, and improve fuel consumption performance, etc.

That is, the combustion chamber structure of the 2.C combustion engine according to the present invention has a line connecting the center of the intake port in the direction of the cylinder row and the outer edge of the exhaust port, and perpendicularly intersects the cylinder row. Lines and,
An ignition plug is disposed in an area surrounded by the outer edge of the intake port and the outer edge of the exhaust port, and a guide wall extending toward the inner circumferential side of the cylinder is provided on the ignition plug side portion of the periphery of the combustion chamber.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

In FIGS. 3 and 4, 11 is a cylinder block, 12 is a cylinder head, 13 is a rocker cover, and 'l: cylinder head 2 has a hemispherical combustion chamber 1.
4 is recessed, and an intake passage 15 and an exhaust passage 16 are arranged in a cross-flow form with respect to the combustion chamber 14, and are connected to an intake port 17 and an exhaust port 18, respectively, which open into the combustion chamber 14. . Reference numerals 19 and 20 indicate an intake valve and an exhaust valve for opening and closing the intake port 17 and the exhaust port 18, respectively. Here, the intake passage 15 is oriented in a direction that is biased to one side from the cylinder axis, and specifically, as shown in FIG. The combustion chamber 14
This is done so as to cause an intake swirl in the direction of arrow S.

On the other hand, one ignition plug 21 is provided in each cylinder, as shown in FIG. 3, as shown in FIG. , a line t2 passing through the outer edge of the exhaust port 18 and perpendicular to the cylinder row direction, and the outer edge of the intake/port 17 and the outer edge of the exhaust port 18 (area A (the area shown with diagonal lines in FIG. 3). Furthermore, this spark plug 21 can be attached to and detached from the cylinder block 12 from the intake side as shown in FIG. It has become.

In addition, in the ignition plug 21 side portion of the periphery of the combustion chamber 14,
A guide wall 22 extending in an arcuate manner is provided on the inner peripheral side of the cylinder. This guide wall 22 is formed almost between two points where a line t3 connecting the center 01 of the intake port 17 and the center 02 of the exhaust port 18 intersects with the periphery of the combustion chamber 14, and its width is The width along the vertical direction in FIG. 4 gradually becomes wider from both ends toward the center. As a result, the combustion chamber 14 has a relatively compact shape, and in particular, the depth of the combustion chamber near the spark plug 21 is ensured to be large.Furthermore, by forming the guide wall 22, the squish area B is substantially reduced. The area of this squish area B is 0.1 of the cross-sectional area of the cylinder bore.
Approximately 5 to 0.25 is appropriate.

FIG. 5 schematically shows a fuel injection device as an example of a fuel supply mechanism that supplies air-fuel mixture from the intake manifold 3.
In addition, an air flow meter 331, engine speed sensor 34, 02 sensor 35. Cooling water temperature sensor 36. The control circuit 38 feedback-controls the injection amount based on various signals from the throttle switch 37 and the like, and supplies a relatively lean air-fuel mixture close to the stoichiometric air-fuel ratio to the intake passage 15.

Now, in the combustion chamber structure configured as described above, the intake air-fuel mixture is guided into the intake path 15 and flows into the combustion chamber 14 in a substantially tangential direction, creating a swirl in the combustion chamber 14 in the direction of arrow S. cause it to occur. At this time, since the intake passage 15 is slightly curved in front of the intake port 17, the mixed air flow does not directly hit the cylinder bore wall and flows cleanly along the bore wall, so that the inflow resistance is small. Furthermore, as is clear from the positional relationship between the intake port 17 and the spark plug 21, the incoming air-fuel mixture does not directly hit the spark plug 21, and the liquid fuel in the air-fuel mixture may be absorbed into the intake port by the curvature of the intake passage 15. Since most of the spark plugs are unevenly distributed on the outer peripheral side of the cylinder 17, they do not hit the spark plug 21 located on the opposite side.

On the other hand, the male whirl S generated in the combustion chamber 14 is removed from the exhaust port 18.
As a result of flowing along the guide wall 22 from the vicinity, the flow velocity is increased. That is, by activating the flow near the spark plug 21, it is possible to reliably ignite a relatively lean fX mixture, and it is also possible to speed up flame propagation and stabilize combustion. In addition, as mentioned above, since the combustion chamber 14 has a compact shape due to the formation of the guide wall 22, knocking is less likely to occur due to the strengthened swirl, and a high compression ratio (for example, about 91 to 94) can be achieved. It is possible to advance the ignition timing.

Therefore, the misfire limit air-fuel ratio of the engine is increased to 20 or more due to the synergistic effect of these factors, making it possible to operate near the stoichiometric air-fuel ratio at high speeds. Significant improvement in fuel consumption can be achieved.

As is clear from the above explanation, according to the combustion chamber structure of the internal combustion engine according to the present invention, it is possible to prevent the ignition plug from smoldering or misfire due to direct impact of the inflowing ai, and to use a relatively rare mixture of R. This makes it possible to achieve better fuel efficiency and better combustion, making it possible to further improve fuel consumption performance and exhaust characteristics.

[Brief explanation of the drawing]

1 and 2 are plan views showing an example of a conventional combustion chamber structure, FIG. 3 is a plan view showing a combustion chamber structure according to the present invention, FIG. 4 is a sectional view thereof, and FIG. 5 is a plan view thereof. FIG. 2 is a configuration explanatory diagram showing an example of a fuel supply mechanism. l2...Cylinder head, 14・■Combustion chamber, 150・
Intake passage, 16...Exhaust passage, 17...Intake port, 1
8-... Exhaust port, 21- Bones and spark plugs, 22... Guide wall. Figure 1 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] (1) An intake passage and an exhaust passage are arranged in a cross-flow shape in a hemispherical combustion chamber equipped with an intake port and an exhaust port, and the intake passage is oriented toward a position offset to one side from the cylinder axis. In the combustion chamber structure of an internal combustion engine, ignition occurs in an area surrounded by a line connecting the center of the intake port in the direction of the cylinder row, a line passing through the outer edge of the exhaust port and perpendicular to the cylinder row, and the outer edge of the intake port and the outer edge of the exhaust port. A combustion chamber structure for an internal combustion engine, characterized in that a plug is provided, and a guide wall extending toward the inner circumferential side of the cylinder is provided on the ignition plug side portion of the periphery of the combustion chamber.